Make quad face from where two edges will meet?
If you have the F2 addon enabled (comes bundled with blender), you can do exactly what you are looking for.

To enable the F2 addon, open up the user preferences with CtrlAltU or File > User preferences. Then in the Addons tab, search for f2. Enable the addon by checking the check box.

Now you can simply select the corner vertex, and press F. Done.



Do note that the addon decides which direction to make the new face based off of the mouse position.


  Direction control
  
  If there are multiple ways to create a new quad, the position of the mouse cursor is taken into account. Of the multiple new faces which are possible, the one which will be closest to the mouse cursor (in 2d screen-space) is the one which will be created. 


Quoted from the wiki

Further documentation can be found on the addon's home page.